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Mitral Regurgitation

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Overview

Mitral regurgitation (MR) is the result of the mitral valve failing to close properly, leading to leakage of blood from the left ventricle through the mitral valve and back into the left atrium when the left ventricle contracts.

People with mild-moderate MR may be asymptomatic for a long time, but as the disease progresses, the myocardium hypertrophies leading to left ventricular dysfunction and heart failure.

Causes

Epidemiology

  • MR is the second most prevalent valve disease after aortic stenosis
  • MR is associated with increasing age, female sex, low BMI, renal dysfunction, myocardial ischaemia, and previous mitral valve prolapse

Causes

  • Post-myocardial infarction
  • Cardiovascular disease
  • Mitral valve prolapse
  • Infective endocarditis
  • History Rheumatic fever
  • Hypertrophic cardiomyopathy

Presentation

They key examination finding is a pansystolic (holosystolic), blowing murmur at the apex that radiates to the axilla.

Chronic mitral regurgitation may have:

  • No symptoms
  • Shortness of breath on exertion
  • Decreased exercise tolerance
  • Peripheral oedema – typically the lower limb
  • Palpitations
  • Features of left ventricular dysfunction e.g. orthopnoea/paroxysmal nocturnal dyspnoea

Acute mitral regurgitation leads to rapid pulmonary oedema and is a medical emergency, as it can be life-threatening. This requires emergency valve repair surgery.

Differential Diagnoses

Tricuspid regurgitation

  • Mitral regurgitation is louder on expiration
  • Tricuspid is louder on inspiration

Investigations

All patients

  • ECG:
    • May show underlying arrhythmia or previous infarction
    • May show broad P waves, which suggest atrial enlargement
  • Transthoracic echocardiogram:
    • Identifies mitral regurgitation

Management

Acute mitral regurgitation

  • 1st line: emergency surgery:
    • They may need preoperative diuretics: furosemide is used
    • Surgical options are: annuloplasty, bioprosthesis/mechanical valve replacement

Asymptomatic chronic mitral regurgitation

  • Depends on left ventricular ejection fraction (LVEF):
    • If LVEF >60%: 1st line: ACE inhibitors and beta-blockers
    • If LVEF ≤60%: surgery

Symptomatic chronic mitral regurgitation

  • LVEF ≥30%:
    • Surgery and ACE inhibitors + beta-blockers + diuretics (furosemide or indapamide)
    • Surgical options are: annuloplasty, bioprosthesis/mechanical valve replacement
  • LVEF <30%:
    • ACE inhibitors + beta-blockers + diuretics (furosemide or indapamide)
    • Surgery is not indicated due to significant operative risk

Complications

Prognosis

  • Acute MR has a poor prognosis if not treated promptly
  • Coronary artery disease and LV dysfunction are associated with a worse prognosis

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